The present invention constitutes an improvement in the system disclosed in my prior U.S. Pat. No. 4,176,307 issued Nov. 27, 1979, for "Energy Economizing AC Power Control System" and, more particularly, relates to a system which produces results similar to those achieved in my prior patented system but does so by means of a circuit which is far simpler.
The disclosure of my said prior U.S. Pat. No. 4,176,307 is incorporated herein by reference. It teaches an arrangement which is capable of reducing the iron and copper losses in an induction motor when the motor is operating at less than full rated load. This prior system incorporates a wave modifier which is operative to apply full sine waves of voltage from an AC power source to the stator winding of an induction motor during rotational start-up and speed build-up of the motor and, as the motor approaches full speed, the said prior system then operates to vary the electrical angle of each cycle of the power source which is actually coupled to the stator winding to provide varying fractions of each sine wave of voltage from the power source to the stator winding in accordance with the energy requirements imposed on the motor by the rotor load at any given moment. The system thus functions to substantially reduce the iron and copper losses of the induction motor by causing the average current supplied from the power source to the stator winding to be supplied primarily as a function of the load on the motor as said load varies.